I doubt I'll convince the parent, but for the curious about why this comment is utterly wrong and uninformed let's look at how muscles work.
In a given set of muscles you have dozens to thousands of motor units. Each is activated by a motor neuron. When recruited the muscle fibers in a motor unit begin producing (or trying to produce) force. The interesting thing is that they arn't all recruited at the same time, when you use 'a muscle' your actually invoking a complex process of recruitment of sub units within that muscle. Moreover these units are not created equally. Some can produce force for a long period of time and are usually weaker, some can produce force very rapidly but tire quickly. This is why when you try to produce a small static force for a long period of time (e.g. hold your arms out straight) your muscles will eventually start shaking and eventually give out. As one set of motor units begin to fatigue the signal to the whole muscle increases, recruiting fast action motor units which are worse at slow holding, and eventually they and all the units are fatigued and you can't produce continued force.
If you'd like to play around with a simulation of the above process you can, it's older code but it may still check out:
And to specifically address the issue of 'building muscle', as I've noted there are lots of sub components with different roles. Each of those can grow over time for different reasons and fatigue is one of the main signals for growth. Not the only one, but the notion that the only way to build muscle is to 'tear up' your muscles with huge lifts is both outdated and wrong.
I'm having trouble understanding how your comment refutes mine; could you clarify?
> Not the only one, but the notion that the only way to build muscle is to 'tear up' your muscles with huge lifts is both outdated and wrong.
I think you're misunderstanding my point. The bodyweight squat is ineffective because you cannot change the stimulus; the only training variable you can adjust is the number of squats you do. Because it's a relatively easy exercise, this quickly means that you cannot subject yourself to sufficient stress with it, both for myofibrillar and sarcoplasmic hypertrophy purposes. Nobody in the history of the universe has ever gotten big and strong on bodyweight squats. It has never happened and it never will happen.
You sure can change the stimulus. Three options immediately come to mind. First, you can increase the power with which you explode out of the bottom, that is push at the ground harder and faster. Second, you can pause at the bottom for a variable length of time, adding an isometric element and increasing the difficulty of the concentric movement. Third, you can do one legged squats to greatly increase the weight per leg.
Have your heavy barbell back squats made your legs and core strong enough to do explosive pistol pause squats?
In a given set of muscles you have dozens to thousands of motor units. Each is activated by a motor neuron. When recruited the muscle fibers in a motor unit begin producing (or trying to produce) force. The interesting thing is that they arn't all recruited at the same time, when you use 'a muscle' your actually invoking a complex process of recruitment of sub units within that muscle. Moreover these units are not created equally. Some can produce force for a long period of time and are usually weaker, some can produce force very rapidly but tire quickly. This is why when you try to produce a small static force for a long period of time (e.g. hold your arms out straight) your muscles will eventually start shaking and eventually give out. As one set of motor units begin to fatigue the signal to the whole muscle increases, recruiting fast action motor units which are worse at slow holding, and eventually they and all the units are fatigued and you can't produce continued force.
If you'd like to play around with a simulation of the above process you can, it's older code but it may still check out:
https://github.com/iandanforth/pymuscle
And to specifically address the issue of 'building muscle', as I've noted there are lots of sub components with different roles. Each of those can grow over time for different reasons and fatigue is one of the main signals for growth. Not the only one, but the notion that the only way to build muscle is to 'tear up' your muscles with huge lifts is both outdated and wrong.